<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .box {
        width: 300px;
        height: 300px;
        background-color: red;
      }
    </style>
  </head>
  <body>
    <div class="box"></div>
    <script>
      const oBox = document.querySelector(".box");

      function center(e) {
        console.log("center");
        console.log(e);
        console.log(this);
      }
      oBox.onmousemove = throttle(center, 300);

      function throttle(fn, time) {
        let lastTime = 0;
        return function (e) {
          let nowTime = Date.now();
          //书写一个看门狗
          if (nowTime - lastTime < time) {
            return;
          }
          lastTime = nowTime;

          center.call(this, e);
        };
      }
    </script>
  </body>
</html>
